The first volunteer in the Americas joined the VUMC study in April 2016. Since then 69 volunteers — nearly a third people of color — have enrolled through the Vanderbilt HIV Vaccine Program. Researchers hope to meet the program’s goal of 78 volunteers in the next six months.

The study seeks healthy, HIV-negative men and transgender people between the ages of 18 and 50 who have sex with men or transgender partners. This group is at particularly high risk of being infected by HIV.

“It’s really important we engage people of color because they are disproportionately affected,” said Vic Sorrell, community engagement manager for the Vanderbilt HIV Vaccine Program. “It’s estimated that one in two African-American men who have sex with men will contract HIV in their lifetimes if the trajectories go uninterrupted.”

AMP does not utilize a vaccine. Instead a “broadly neutralizing” antibody is injected.

The antibody was isolated from an individual who had an unusual capacity to fight off the virus, said Spyros Kalams, M.D., principal investigator of the Vanderbilt HIV Vaccine Trials Unit. In addition to its unique ability to neutralize many HIV strains, it lasts a long time in the body.

“This study will help us understand the properties of antibodies that lead to protection from HIV infection, and help us determine the types of immune responses we need to measure in future vaccine trials,” said Kalams, associate professor of Medicine and Pathology, Microbiology and Immunology.

Volunteers are divided randomly into three groups. One group receives a low dose of antibody, the second group, a higher dose and the third group, a placebo, an inactive solution. Participants receive an intravenous infusion every eight weeks over the course of the study, about two years.

It’s not known what makes this antibody so potent, Kalams said, but “it could be part of a broad-based strategy to prevent HIV infection.”

“This study is the most exciting thing I’ve done in my career,” said clinic coordinator Kyle Rybczyk, MSN, FNP, who has been with the HIV Vaccine Program since 1992.

“You have to be an eternal optimist to stay in this field,” he said. Studies like this “keep me going.”